Pilot structure for pot type burners



Aug. 31, 1948. J, w. MILLER EI'AL 2,443,148

PILOT STRUCTURE FOR POT TYPE BURNERS Filed Sept. 24. 1942 ZSheets-Sheet1 O O O O .0 30

OO O O o O 0 O 0 O OO/IS o o o o a Q o o 0 o l O O O O 0 O O D G 0 0 2334 24 FIG.2 v 26 'JOHN XI MIL'E'E' OR BY WALDO asmm Y 948. J. w. MILLERETAL 2,448,148

I PILOT STRUCTURE FOR POT TYPE BURNERS Filed Sept. 24, '1942 2Sheets-She et 2 Patented Aug. 31, 1948 PILOT STRUCTURE FOR POT TYPEBURNERS John W. Miller and Waldo G. Smith, Lansing, Mich., asslgnors toMotor Wheel Corporation, Lansing, -Mich., a corporation of MichiganApplication September 24, 1942, Serial No. 459,500

21. Claims.

This invention relates to burners of the vaporizing pot type andconstitutes an improvement in such burners.

This application is a continuation in part of our prior co-pendingapplication Serial No. 410,- 498, filed September 12, 1941, nowabandoned.

Burners of the vaporizing pot type are those burners which comprise apot having a plurality of uniformly spaced apart air inlet openings inthe side walls and in which the heat output can be-varied according tothe demand on the heating system merely by varying the rate at which thefuel is supplied to the burner.

The principal problem met with in burners of the vaporizing pot typelies in producing a clean and stable fire at all stages of operation,that is, low fire, high fire or various intermediate stages.

To produce such a clean and stable fire the burner must be designed sothat edd currents are substantially eliminated at all of the stages ofoperation of the burner without interfering with 'what is called pilotfire because eddy currents do form below the partition and either causea smoky sooty flame or at times completely extinguish the flame. natesthis condition, permitting a very low turn down of the fuel supply witha resulting clean and stable fire without in an way interfering with thenormal operation of the burner at the higher stages of operation.

This result is accomplished by partially enclosing a portion of theburner adjacent the fuel inlet and below the partition. The enclosure isformed by the burner side wall, the bottom wall. a pair of uprightnon-intersecting baiiies positioned on opposite sides of the fuel inletopening and certain of the air inlet openings, and an upper bafflewhich, in the cases where a partition is employed, is that partition.For best results the volume of the portion of the burner included in theenclosure should be about 3% to 5% of the total volume of the burner,and in any event, less than 10% of the volume of the burner. 'Also, theratio between the totalarea of the air inlet open- The present inventionelimiings directly communicating with the enclosure and the total areaof all of the air inlet openings to the burner should be slightlygreater than the ratio between the volume of the enclosure and the totalvolume of the burner. In other words, slightl more air per unit ofvolume should be admitted directly to the enclosure than to the burner.

With such an arrangement, the formation and circulation of eddy currentsin the zone around the inlet openings are thus effectively prevented andthe fire burns evenly and cleanly at the fuel flow of 25% to 40% lessthan that required to maintain a clean and stable fire without theinvention. A substantial saving in fuel when little or no heat isdesired is thus effected.

Referring now to the drawings:

Figure 1 is a cross-sectional view of a embodying the invention;

Figure 2 is a cross-sectional view on an enlarged scale of the burnershown in Figure 1;

Figure 3 is a cross-sectional view taken on substantially the line 3-3of Figure 2;

Figure 4 is a cross-sectional view of a burner embodying a slightlymodified form of the invention;

Figure 5 is a cross-sectional view taken on substantially the line 55 ofFigure.4: and

Figure 6 is a plan'view of the baffle which forms a part of theenclosure about the fuel inlet opening.

heater The invention is shown in Figures 1 to 3 as embodied in a radiantheater comprising a casing having a combustion chamber ill and an airjacket Ii. The combustion chamber is provided with an access door I2 andhas a flue outlet II. The casing is supportedon legs I4. end of thecasing is open to admit air to the air Jacket ll.

A burner I5 is inountedin the air Jacket H. The side wall of the burneris held in place within the air jacket andtightly against the casing bymeans or a screw it threaded through the legs The burner i5 comprises asheet metal side wall I! in substantially cylindrical form. Adjacent theupper edge of the side wall are two beads, an inwardly extending beadl8, and aboveit an outwardly projecting bead iii. A horizontal row ofuniforml spaced apart secondary air inlet openings 20 is formed in thebead is so that the openings 20 are inclined upwardly and inwardly.Between the bead i8 and the lower edge of the side wall i! .are sixsubstantially evenly spaced horizontal rows of substantially uniformlyspaced The lower apart primary air inlet openings ii. In one side of theside wall, just above the lowermost row of primary air inlet openingsII, is a concavity 22. the purpose of which will appear presently.

A cup shaped bottom wall portion 23 is welded to the bottom edge of theside wall II. The bottom wall is slightly concave. A fuelinlet opening24 is provided at the side of the cup shaped bottom wall and is locateddirectly below the concavity 22.

A fuel supply pipe 24 (see Figure 1) having a metering valve 25a thereinis threaded into the opening 24. Directly below the opening 24 is a well26 to retain fuel at periods of extreme low or pilot fire.

A centrally apertured top wall 21 rests upon the bead is. Ananti-explosion baille it is seated upon the top wall 21 to direct aportion of the secondary air entering the air inlet openings II towardthe aperture in the top wall.

Lying wholly between the lowermost and the uppermost rows of primary airinlet openings II is a partition 28 which divides the burner into alower chamber 3i and an upper chamber-'12. The partition has a largecentral opening it to permit air, vapors and products of combustion topass from the lower chamber to the upper chamber. The partitionpreferably is inclined as shown. Its lower edge is provided with aprojection II which fits into the concavity 31 to position the partitionin the burner, and is thereby located just above the lowermost row ofair inlet openings. The upper edge of the partition rests against theside wall at about the level of -th fifth row of openings.

Below the partition and extending downwardly toward the bottom wall aretwo upright bames 34. The babies 14 are imperforate. Preferably .theyare integral with the partition. The bailies 34 are located on oppositesides of the fuel inlet opening 24 and are spaced apart sufficiently toinclude some primary air inlet openings ll betweenthem. The outer andbottom edges of the bailles 34 are juxtaposed to the side wall I! andbottom wall 23 of the burner. Together with the partition 20, side wallII, and bottom wall 23 they provide a partial enclosure for the portionofthe burner adjacent the fuel inlet. The enclosure is open at itsradially inner vertical side.

Preferably .the baiiles 84 are arranged radially of the burner toeliminate any possibility of air entering the adjacent openings 2iimpinging on them and causing a smoky flame.

Preferably the Danes 34 are arranged at an angle to each other ofapproximately 80 to 85 degrees. With the partition 2! inclined as shown,the volume of the. enclosure formed by the partition, the bai'lles I4and the side and bottom'walls of the burner will be about 3% to 5% ofthe total volume of the burner.

Only certain holes'of the lowermost row of air inlet openingsnvilldirectly communicat with the enclosure. Ifthe baiiies 84 are arranged asindivcated above, there will be six of these openings and their areashould be approximately 5% to 6% of the total area of the air inletopenin s in'the burner side wall. Thus. it will be' seen that thepercentage of the area of the air inlet openings communicating directlywith the enclosure is slightly greater than the percentage of the volumeof the enclosure itself. This will assure adequate air for combustion atpilot fire.

In operating the burner, the metering valve is opened sufficiently topermitfuel to flow into the burner where it collects in the bottom ofthe burner. The fuel is ignited in any suitable way such as by insertinga lighted taper through the access door it. For a short time combustionwill occur directly on the surface of the pool of fuel until suflicientheat is generated to vaporize a portion of the fuel. These vapors mixwith the air entering the air inlet openings II from the air Jacket iiand the flame will move away from the surface of the pool of fuel in thebottom of the burner.

The rate of combustion can be varied by adlusting the metering valve toregulate the flow of fuel. In doing that th zone in which combustion isinitiated can be varied. Thus, combustion may, in a general way, beinitiated within the enclosure (low fire), outside oi the enclosure butwithin the lower chamber 3| (low intermediate fire), within the upperchamber 32 (high intermediate fire) or at the opening in the top wall 21(high flre). The latter is the upper limit of combustion initiation.

While for the sake of convenience in description the burner has beendivided into the four zones Just mentioned, it will be understood thatthere is no sharpline of demarcation between these zones. The combustioncan be more closely regulated than that. It will also be understood thatat low fire, combustion is not necessarily restricted to that part ofthe burner immediately on or over the well 26. The fire may spread outmore into the enclosur about the fuel inlet opening.

As previously stated, the present invention has to do with improving theoperation of the burner at low fire. In the devices ofthe prior art whenoperating at a low flre such, for example, as an oil flow of 300 c. c.per hour or less in a typical burner, the flame moves from one part ofthe burner to another and is extremely unstable. As th flow of oil isdecreased from approximately 300 c. e. per hour the combustion reaches acritical point where when the flre moves from one part of the burner toanother it may become extinguished. Moreover, throughout this low firerange of operation. because of the instability of the flame, there is animproper mixing of air with the oil vapors so that a smoky flame isproduced.

Figures 4 to 6 disclose a somewhat modified form of the invention. Theburner itself is substantially the same as that previously disclosed. Itcomprises a bottom wall ll having a fuel inlet opening ll formed in theside thereof adjacent the bottom. A tubular side wall it is welded tothe upper edge of the bottom wall ll. The side wall is provided with sixhorizontal rows of air inlet openings I.

Near the upp r edge of the bln'ner' side wall are two rows of secondaryair inlet openings 4, the same as in the previously described burner.

A top wall 5! and. an anti-explosion bailie it identical with thosepreviously described are mounted in the burner adjacent the secondaryair inlet openings and above the uppermost primary air inlet openings.

, A centrally apertured partition 51 is mounted in the burner. Thepartition is an annulus having an aperture II at its center. It will benoted that the portion of the partition located above the fuel inletopening ii is inclined upwardly in exactly the same manner as thepartition 2!, but the upper part of the partition is arrangedhorizontally intermediate the third and fourth row of air inlet openingsfrom the bottom. The

partition I1 is the same as that disclosed in the oo-pending applicationof John W. Miller and Raymond E. Fell, Serial No. 407,850, flied August22, 1941, and issued November 9, 1943, as Patent Number 2,334,117. ,Thispartition operates somewhat better than the wholly inclined partition ofFigures 1 to 3. In and of itself it is not a part of this invention.

Instead of making the upright bafiies integral with the partition, as inthe case of Figures 1 to 8, a separate baffle construction is employedin the device of Figures 4 to 6. This bailie' is shown in its entiretyin Figure 6. It is a one piece inverted channel shaped constructionhaving a web I. inclined upwardly at the same inclination as that of theinclined part of partition 51, and a pair of vertical legs or fi-anges10. These legs are arranged so that their lower edges rest upon titionor may be welded or otherwise attached thereto.

The legs of the channel are arranged radially of the burner and at anangle to each other of approximateley 80 to 85 degrees, as in the caseof the baiiies 34. Thus, the percentage of the volume of the enclosureformed by the bottom wall and side wall of the burner and the uprightfrom the burner side wall.

legs II is approximately 3% to 5% of the total volume of the burner,exactly as in the case of the previously described modification.

The operationof the ,device shown in Figures 4 to 8 is identical to thatshown in Figures 1 to 3.

At the low fire stage ofoperation of the burner described above thebaffles of the present invention effectively prevent the circulation ofeddy currents in the zone around the fuel inlet opening and therebypermit combustion to occur at low fire without the formation of soot. Mthe same time the bafile construction prevents extinguishment of theflame when at very low fire by preventing drafts 'due to such eddycurrents. On the other hand, the baffle construction does not preventspreading out of the fuel across the bottom of the burner at greaterrates of fuel flow and does not in any way interfere with the effectivevaporization of the fuel or the mixing therewith of the air forcombustion.

From-a practical standpoint at any stage of the operation of the burnerabove pilot fire the baille construction is virtually non-existent.fact, at low fire the small portion of the burner within the enclosureacts as a tiny vaporizing pot type burner with a resultant clean andstable fire therein, and yet becomes an integral portion of the muchlarger burner when the burner is operating at the higher stages. ofcombustion.

The structure is exceedingly simple and economical to manufacture andinstall. Furthermore, the modification shown in Figures 4 to 8 can beinstalled in existing burners having partitions or in burners having nopartition at all, with a consequent increase in efficiency there-- turein the partition.

of spaced apart air inlet openings therein and a fuel inlet opening inthe burner adiacent one side thereof, means cooperating with said'bottom and side walls for partially enclosing a per 'tion of theinterior of the burner adjacent said fuel inlet opening, said meanscomprising a pair of spaced apart non-intersecting upright bafflespositioned on opposite sides of said fuel inlet opening and certain ofsaid air inlet openings and a. third bailie engaging the upper ends ofsaid pair of baiiles and lying wholly between the uppermost andlowermost air inlet openings, all of said bailles extending transverselyof the burner, one upright edge of each bai'iie of said pair beingjuxtaposed to the burner side wall and the other upright edgebeingspaced a substantial distance 2. A burner as defined in claim 1wherein said third baille is a centrally apertured annulus having itsperipheral edge in substantially ,continuous engagement with the burnerside wall.

3. A burner as defined in claim 1 wherein said pair of baiiles engagesthe bottom wall of the burner.

4. A burner as defined in claim 1 wherein said third bai'ile is acentrally apertured annulus and said pair of bailles engage the bottomwall of said burner.

5. A burner as defined in claim 1 wherein said third 'baflle is acentrally apertured annulus and said pair of bafiies'extend radially ofthe burner from the side wall to the edge of the aperture in theannulus.

6. A burner as defined in claim 1 wherein said pair of baiiles arearranged radially of the burner.

7. A burner as defined in claim 1 wherein said pair of bailles areimperforate.

8. In a burner of the vaporizing pot type wherein combustion can belocalized in different parts thereof by regulating the fuelsupplied'thereto, said burner comprising a bottom wall. a tubular sidewall having a plurality of spaced apart air inlet openings therein and afuel inlet opening in the burner adjacent one side thereof, a centrallyapertured partition extending across the burner and located whollybetween the lowermost and uppermost air inlet openings, and a pair ofspaced apart non-intersecting upright bailles on opposite sides of saidfuel inlet and certain of said air inlet openings, said baiiiesextending fromsaid side walls toward the aperture in the partition, saidbailies being positioned between said partition and the bottom wall ofthe burner and cooperat ing with said bottom wall, side wall andpartition to partially enclose a portion of the burner adjacent the fuelinlet opening, said enclosure being open at its radially inner andadjacent the aper- 9. A burner as defined in claim 8 wherein saidbalile's extend radially of the burner.

10. A burner as defined in claim 8 wherein said baii'lesmre integralwith said partition.

11. A burner as defined in claim 8 wherein the baffles engage thepartition, the bottom wall and the burner side wall.

12. A burner as defined in claim 8 wherein said bailles converge fromthe fuel inlet opening toward the center of the burner.

13. In a burner ofthe vaporizing pot typecomprising a bottom wall, atubular side wall having a plurality of spaced apart air inlet openingstherein and a fuel inlet opening in the burner adjacent one sidethereof, and bafile means cooperating with the bottom wall and side wallof the burner'to partially enclose a portion of the latter adjacent thefuel inlet opening, said bame means comprising an inverted channelmember having the legs thereof located on opposite sides of the fuelinlet opening and certain of said air inlet openings, one end of saidchannel member being juxtaposed to the burner side wall and the otherend of said channel member being located adjacent the center of theburner.

14. In a burner of the vaporizing pot type comprising a bottom wall, atubular side wall having a plurality of spaced apart air inlet openingstherein and a fuel inlet opening in the burner adjacent one sidethereof, a certainly apertured partition extending across the burnerabove said fuel inlet opening and located wholly between the uppermostand lowermost air inlet openings, and baiile means cooperating with thebottom wall and side wall of the burner to partially enclose a portionof the latter adjacent the fuel inlet opening, said baille meanscomprising an inverted channel member positioned beneath said partition,one end of said channel member being juxtaposed to the burner side wallwith the legs of said channel positioned on opposite sides of said fuelinlet opening and certain of said air inlet openings and the other endof said channel member being, positioned adjacent the opening in thepartition, the web of the channel member engaging the under side of thepartition and above said fuel inlet opening, and a pair of lugs integralwith the partition engaging the channel member to hold the same inposition relative to the burner.

15. As an article of manufacture, a low fire pilot for use incombination with an oil burning vaporizing pot type burner of the typecomprising a chamber having a bottom wall, generally upright side wallsperforated to admit air to support combustion and an oil admissionopening for delivering oil onto the bottom wall of the chamber; saidpilot comprising structure including a top'wall and downwardly extendingside walls forming an inverted channel open at opposite ends, said sidewalls of the pilotvstructure being adapted to rest uponthe bottom wallof the pot and in a position to cover the oil delivered, for pilotpurpose, to the bottom wall of the pot, said structure being positionedso that one open end of the channel registers with certain of theperforations in the side walls of thepot and the upright ends of theside walls of last mentioned end of structure are juxtaposed with theupright side walls of the pot, certain of the walls of the pilotstructure converging toward one another from the last mentioned end ofthe pilot structure toward the other open end thereof.

mission of the fuel to the pot and defining a space in communicationwith a plurality of the lower primary air inlet apertures of the pot,said.

housing including generally upright inwardly converging side wallsdefining a flame outlet at their convergence, and extending inwardlyfrom the pot wall, and means for delivering liquid fuel to the pot at apoint enclosed by said pilot housing.

8 17. in combination, an open topped burner pot having a circumferentialwall provided with a plurality of primary air inlet apertures located atvarious levels in the wall, means for delivering secondary air to themixture ofprimary air and vaporized fuel moving upwardly through the potand a pilot housing surrounding the area of admission of the fuel to thepot and defining a space in communication with a. plurality of the lowerprimary air inlet apertures of the pot, said housing including generallyupright inwardly converging side walls defining a flame outlet at theirconvergence, and extending inwardly from the circumferential ot wall,and cover means for said housing, said cover means located below thelevel of the highest of the primary air inlet apertures and below thelevel of admission of secondary air to the mixture, and means fordelivering liquid fuel to the pot at a point enclosed by said pilothousing.

18. In combination, an open topped burner pot having a circumferentialwall provided with a plurality of primary airinlet apertures located atvarious levels in the wall, means for delivering secondary air to themixture of primary air and vaporized fuel moving upwardly through thepot and a pilot housing surrounding the area of admission of the fuel tothe pot and defining a space in communication with a plurality of, thelower primary air inlet apertures of the pot, said housing havinggenerally upright, converging side walls and a top wall, the top wallbeing located below the level of the highest of the primary air inletapertures and below the level of admission of secondary air to themixture, the inner edges of said side and top walls defining a flameaperture in communication with the interior of the pot, and means fordelivering liquid fuel to the pot at a point enclosed by said pilothousing.

19. A liquid fuel burner comprising. in combination, a combustion pothaving generally upri ht side walls and a connecting bottom wall, saidside walls having upper and lower perforations, said pot being open atthe top; means forming a substantially horizontally extending fuelvaporizingchamber disposed within the pot adjacent the bottom wallthereof, said chamber having an air inlet end, said air inlet end beingdisposed adjacent one side wall of the pot and communicating withcertain of said lower perforations, said chamber having a fuel mixtureoutlet confronting a side wall of the pot opposite said first mentionedside wall; means for supplying liquid fuel to the chamber; and gas andair baflie means intermediate the top and the bottom wall of the pot andextending inwardly from said confronting side wall toward said firstmentioned means and located between said upper and lower perforations.

20. In combination, an open topped burner pot having a circumferentialwall provided with a' plurality of primary air inlet apertures locatedat various levels in the wall, means for delivering secondary air to themixture of primary air and vaporized fuel formed in the pot and a pilothousing surrounding the area of admission of the fuel to the pot anddefining a space in communication with a plurality of the lower primaryair inlet apertures of the pot, said housing including upwardlyextending side walls and a top wall and having, adjacent the inner endsof said side and top walls, a flame outlet of substantially smaller areathan the area of the pot wall which is in register with the interior ofthe pilot housing, the highest part of said pilot housing being locatedbelow the level of the highest of said primary air inlet apertures, andmeans for delivering liquid fuel to the pot at a point enclosed by saidpilot housing.

21. In combination, an open topped burner not having a circumferentialwall provided with a plurality of primary air inlet apertures located atvarious levels in the wall, means for delivering secondary air to themixture of primary air and vaporized fuel formed in the pot, and a pilothousing surrounding the area of admission of the fuel to the pot anddefining a space in communication with a plurality of the lower primaryair inlet apertures of the pot, said housing including generaily uprightside walls and having a flame outlet at the inner ends of said sidewalls, said side walls extending inwardly from the pot wall, and meansfor delivering liquid fuel to the pot at a point enclosed by said pilothousing.

- JOHN W. MILLER. WALDO 6. SMITH.

REFERENCES crrnn The following references are of record in the file ofthis patent:

UNITED STATES PATENTS

